Merge branch '6516_help_system_message_sort_fix' into 'develop'

6516_help_system_message_sort_fix

See merge request ispconfig/ispconfig3!1752

Author: Till Brehm

interface/web/help/templates/support_message_list.htm

@@ -18,7 +18,7 @@ <h1><tmpl_var name="list_head_txt"></h1>
                     <tr>
                         <tmpl_if name="is_admin"><th data-column="sender_id"><tmpl_var name="sender_id_txt"></th></tmpl_if>
                         <th data-column="subject"><tmpl_var name="subject_txt"></th>
-						<th data-column="date"><tmpl_var name="date_txt"></th>
+						<th data-column="tstamp"><tmpl_var name="date_txt"></th>
                         <th class="small-col text-right">{tmpl_var name='search_limit'}</th>
                     </tr>
                     <tr>